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How the measurement actually works
Satellite analysis gets described either as magic or as jargon, and neither helps you judge whether a result is any good. This series takes the chain apart, one step at a time, with visuals you can pull around yourself.
- 01
How light works
A satellite does not photograph the ground, it measures how much light of each wavelength comes back. Drag through the spectrum and watch four surfaces change places.
Read it → - 02
The concept of an index
Two bands, one subtraction, and a number that means something. How a ratio turns raw reflectance into a map you can act on.
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The different types of indices
One river town seen through NDVI, NDWI, NDTI, NBR and NDBI. Each index is a question, and the trick is knowing which one you are asking.
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Stereo imaging
Two viewing angles and the parallax between them. How a flat image pair becomes terrain with real heights, and two dates become a volume.
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Radar and SAR
A sensor that supplies its own light and sees through cloud. Why calm water reads black, why flooded buildings get brighter, and when the trick stops working.
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Scaling a method
You validate in one place. The honest question is how far that result travels, and where it quietly stops being true.
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